Fonualei Volcano | John Seach



18.02 S, 174.32 W
summit elevation 200 m

Fonualei Volcano is located in northern Tonga, 350 km north of Nukualofa. 

Fonualei volcano is a 2 km wide island with a breached crater to SW and a lava flow reaching the sea. The volcano rises from a depth of 1000 m and has mostly cliffs on the coast, except on NW and W where there are small sandy beaches.

A central pyroclastic cone within the caldera is breached on the east. The northern crater rim is the island summit.

Fonualei Island has a narrow fringing reef on the NE, S, and W sides. The volcano has violent eruptions every 40-50 years.

1943 Eruption
Explosion pits on the west side of the 1939 lava dome and within the central crater ejected angular blocks of glassy lava, weighing up to a few tons. The eruption was limited to a few large phreatic explosions.

1939 Eruption
An eruption in 1939 produced a broad lava flow which reached the sea through a breach in the caldera wall on the southwest side of the island.

1846 Eruption
The island was in part destroyed by the eruption of its crater and ash fell in large quantities on passing ships 500-600 miles to the N.E.

Further reading
Bryan, W.B., Stice, G.D. and Ewart, A., 1972. Geology, petrography, and geochemistry of the volcanic islands of Tonga. Journal of geophysical research77(8), pp.1566-1585.

Brodie, J.W., 1970. Notes on volcanic activity at Fonualei, Tonga. New Zealand Journal of Geology and Geophysics13(1), pp.30-38.

Spennemann, D.H., 2004. The June 1846 Eruption of Fonualei Volcano, Tonga. The Johnstone Centre, Charles Sturt University: Albury.

Fonualei Volcano Eruptions

1957, 1951, 1943, 1939, 1906, 1846-47, 1791.